1. Field of the Invention
The present invention relates to an illuminating knob used to operate various kinds of switch devices such as electric equipment for a vehicle.
2. Description of the Background Art
An example of an illuminating knob is explained based on the following illustrated example. FIG. 7 is a schematically explanatory view of a partial section of the illuminating knob, wherein the knob is substantially shaped in a bottomed cylinder. A window hole 3 is provided on a bottom portion 2 of a base 1 which functions as a main body made of a resin in which no light penetrates (hereinafter, refereed to as "non-penetration") due to the mixing of colored cosmetics or other material in the resin. An accommodating concave 4 with a hollowed inner side is formed on the bottom portion 2 including the window holes 3.
A lens 5, a transparent colored plate 6 and a louver body 7 are fitted in the accommodating concave 4 and light from a bulb 8 inside of the base 1 passes through the louver body 7. A slit 9 appears inevitably on a peripheral of the louver body 7 owing to a tolerance in the fitting portion.
FIG. 8 is a view showing an example of the louver body 7, wherein a transparent plate 11 is superposed on a louver 10 made of a non-penetration rubber. A marked layer 12, printed with non-penetration black paint, is formed on the transparent plate 11 and an inside of an indicating pattern is eliminated from the marked layer 12. A non-diffusion paint layer 13 is formed on a rear surface of the transparent plate 11.
Another transparent plate 14 is superposed on an opposite surface of the louver 10. The light from the bulb 8 passes through the louver 10 in a state of little dispersion and an indication is accomplished via the light passing through an eliminated portion of the marked layer 12.
At this time, because the dispersion of the penetrating light is lessened owing to the light passing through the louver body 7, such a problem wherein the light penetrates the marked layer 12 and disperses excessively and is reflected on a windshield of a car, is reduced.
The non-diffusion paint layer 13 makes an illuminating light to penetrate in a non-dispersion state when the illumination is not on such as during the daytime, the indication marked on the marked layer 12 is shown clearly by incident light from outside being reflected on the non-diffusion paint layer 13 after passing through the paint eliminating portion of the marked layer 12.
Generally, miniaturization is required for the operating knob of a switch. Especially, in the field of electric equipment for a car, miniaturization in both the dimension and weight of the car itself are required.
In the illuminating knob, the accommodating concave 4 should be formed on the bottom portion 2 where the louver body 7 is mounted to fit as in the above mentioned prior art. An area required for a mounting portion becomes necessarily larger. If the mounting portion is made small as it is, an indication pattern of the indication portion by the penetrating light is made small in proportion to the mounting portion. Thus, it is hard to see the pattern. Therefore, miniaturization of the base 1 has certain limits.
Further, in the mounting of the louver body 7, if the surface of the louver body becomes uneven with a circumferential surface of the mounting concave 4 of the bottom portion 2, the unevenness is apt to spoil an appearance and a touch feeling. Where dust is collected in the slit 9 formed on the circumference of the louver body 7, the appearance is also damaged.